Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mailrus!uflorida!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.std.c
Subject: Re: Two standards problems
Message-ID: <10412@smoke.BRL.MIL>
Date: 16 Jun 89 22:06:09 GMT
References: <178@ixi.UUCP <183@ixi.UUCP> <800@cbnewsl.ATT.COM>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 16

In article <800@cbnewsl.ATT.COM> dfp@cbnewsl.ATT.COM (david.f.prosser) writes:
>	#define XtOffset(p, m) offsetof(*(p), m)

In preparing my previous response to the question, I considered something
similar, but it wasn't clear to me from the draft Standard exactly what
was acceptable for the "type" argument to offsetof().  In particular the
use of
	static type t;
in the Standard bothered me; if one substitutes literally for "type" in
that template, will constructs such as "*(p)" where "p" is a type name
work?  Some types need the identifier "t" buried inside them.  Anyway,
the proper declaration in this case would seem to be
	static p *t;
so shouldn't the "type" argument to offsetof() be "p*"?  I don't think
this was specified clearly enough in the draft (although I would be happy
to be proved wrong on this point).